The invention relates to a transmission including devices for controlling and actuating the transmission, as well as a method of operating the transmission.
A transmission in the sense of the present invention is a mechanism that can be shifted in steps or in a continuous, step-less range into different shift positions corresponding to different transmission ratios between two shafts of the transmission. The transmission can be configured as a gear-shifting transmission or a cone-pulley system, or any other transmission that may benefit from the present invention. The transmission can be shifted automatically or manually, or in a partially automatic or automated mode with the possibility of manual intervention. Depending on the design of the transmission, the shifts from one shift position to another may or may not cause an interruption in vehicle traction.
A transmission in the sense of the present invention is configured in particular as an automatic transmission or as an automated shift transmission.
An automatic transmission in the present context is a transmission in which the shifts are controlled automatically and occur without interruption in the tractive force. The term xe2x80x9cautomatic transmissionxe2x80x9d in the present context specifically refers to transmissions with a planetary gear mechanism.
The term xe2x80x9cautomated shift transmissionxe2x80x9d relates to a transmission that allows automated shifting between different shift positions and is characterized by an interruption in vehicle traction during the shift processes. The automated shift transmission can be equipped with at least one electric motor to actuate the shift movements.
The term xe2x80x9cshift transmissionxe2x80x9d as used in the present context generally relates to a transmission with a track pattern, i.e., a shift pattern with at least one selector track and several shift tracks, with a first shifter element such as a shift finger that is movable along the tracks.
In the context of the present invention, a selector track or shift track can be a physically existing track or a virtual track.
The term xe2x80x9cvirtual trackxe2x80x9d refers to an arrangement where a control device or an actuator device generates signals that allow the first shifter element to move or be moved only along certain track-like paths.
A shift track in the sense of the present invention consists either of one branch that runs in one direction essentially from a defined position on the selector track, or two branches that run in opposite directions from a selector position on the selector track. Movement along a shift track brings the first shifter element to a predetermined position in which a predetermined gear level or a predetermined transfer ratio of the transmission is engaged.
A transmission in the sense of the present invention is equipped with an actuator device, i.e., a device that can apply a force to at least one shifter element that is part of a shift mechanism, so that the shifter element is moved in predetermined ways to shift the transmission into different shift positions.
The actuator mechanism contains in particular at least one electric motor. A preferred arrangement has a first motor used as a selector motor to move the first shifter element along the selector track, and a second motor used as a shifter motor to move the first shifter element in the direction of the shift tracks.
A transmission includes a control device which transmits control commands and/or supplies power to the actuator device. The control commands or the power transmitted from the control device determine the nature, timing, duration, direction and intensity of the action to be exerted by the actuator device on the first shifter element. The control command signals can control the actuator device alone, or they can also control a further device such as a clutch, more specifically an automated clutch device. With preference, the signals transmitted from the control device to the actuator device are in the form of electric currents or voltages.
A transmission in the context of the present invention is also equipped with a position-detecting device.
A position-detecting device is a device that can detect a position or a change in position in absolute or relative terms. In particular, the position-detecting device can measure a travel distance or an angle of rotation or a change in distance or angle from one point in time to another.
The position-detecting device can be based on a principle of absolute or relative measurement. The position-detecting device is configured in particular as an incremental position sensor or an angle-detection sensor.
Preferably, an incremental angle-detection sensor is arranged on an electric motor, specifically the aforementioned shifter motor or selector motor.
Automated shift transmissions are known in which a control device transmits output signals in the form of electric voltages to a selector motor and a shifter motor. The signals can have the effect that the selector and shifter motors actuate a shifter shaft which, in turn, causes shift processes to be performed in the transmission. In a transmission of this kind, incremental displacement sensors are arranged at the selector motor and shifter motor to detect position changes and thereby determine the current shift position of the transmission.
The transmissions of the foregoing description are proven in practical use.
Nevertheless, there have been instances of malfunctions in transmissions of this kind. In particular, the malfunctions were related to the gear-shifting process, causing in some cases damage to the transmission, loss of driving comfort in the vehicle equipped with the transmission, or dangerous traffic situations.
The present invention therefore has the objective of providing a transmission, a control device for controlling the transmission, as well as a method of operating the transmission with the purpose of improving operating safety in a simple and cost-effective way and also offering the possibility of improved driving comfort.
To meet the foregoing objective, the invention proposes a transmission with one or more first shifter elements movable in a track pattern with a selector track and shift tracks and one or more second movable shifter elements. Moving the first and/or second shifter element will set the transmission into different shift positions.
The transmission according to the invention further includes: an actuator device which acts on at least one of the shifter elements, a main position-detecting device to detect the position of one of the movable shifter elements in the directions of the selector track and shift track, and at least one redundant position-detecting device, which can under certain predetermined conditions detect the position of one of the movable shifter elements.
In short, the invention proposes a transmission with a main position-detecting device as well as a redundant position-detecting device.
The main position-detecting device within the context of the present invention is in particular a primary position-detecting device not restricted to any specific configuration.
The shifter mechanism that is part of the transmission has a first shifter element movable in a track pattern, and also a second movable shifter element. Moving at least one of the shifter elements will set the transmission into different shift positions. Specifically, the first shifter element takes the form of a so-called shifter finger, and the second shifter element takes the form of a so-called shifter shaft.
The main position-detecting device, configured in particular as an incremental sensor device, is designed to detect the position of a movable shifter element with regard to the directions of selecting and shifting, i.e., the two coordinates of movement along the selector track and shift tracks.
According to a preferred embodiment of the invention, the main position-detecting device indicates the position with a higher degree of accuracy than the redundant position-detecting device.
The invention shows a way to avoid a continuing use of erroneously detected position data and thereby avoid the risk that the control device will generate erroneous output signals based on the faulty detection data. Furthermore, driving comfort can be improved in a vehicle equipped with the transmission according to the invention.
Preferably, the redundant position-detecting device includes a sensor device capable of generating a sensor signal that is indicative of the position of at least one shifter element, e.g., the first shifter element, and can be transmitted to the control device.
The sensor device can be an electromechanical contact sensor, a Hall-effect sensor, an inductive sensor, an optical sensor, a capacitative sensor, an acoustical sensor, or an electrical slider contact cooperating with conductive tracks, or any other suitable device.
Preferably, the sensor device is based on a digital concept, so that it provides a digital signal. The digital signal indicates whether a predetermined movable shifter element such as the aforementioned first or second or another shifter element of the transmission is positioned in a first or second range of possible shift positions. The first and second range can themselves be subdivided into partial ranges that may be adjacent to each other or spatially separated from each other.
With preference, the sensor device is configured with at least three steps, so that the sensor device can generate a distinctive sensor signal in each of the three steps to indicate the range of shift positions where the shifter element is currently located. The sensor output signals for different shift positions can be identical or different from each other.
The sensor device may work in a continuous, step-less range or in steps, indicating the shift positions of the transmission in discrete steps or in a continuous, analog format.
According to a preferred embodiment of the invention, at least a part of the shift positions that the transmission device or a shifter element can be set to is associated with corresponding positions of a field, a field-like area, or a curve profile or surface profile.
The preferred embodiments of the present invention will be presented schematically, using the concept of the field, field-like area, or surface profile. Each of the embodiments according to the invention can comprise a field as well as a field-like area, or also a surface profile.
A field in the sense of the present invention exists either as a material or non-material field in one, two, three or more dimensions. The term xe2x80x9cfieldxe2x80x9d in the present context means one or more physical quantities that vary as a function of location, i.e., of the spatial coordinates in an area where the field is defined. If the field is defined by more than one variable physical quantity, such quantities may or may not be dependent on each other.
With preference, at least one shifter element of the transmission is subjected to a field, with predetermined shift positions of the shifter element being assigned to predetermined field locations.
The field can in particular consist of an acceleration field, or an electrical, magnetic, or other kind of field.
A preferred kind of field in the sense of the present invention consists of a surface profile arranged in particular on the surface of the second shifter element. The profile has raised and depressed portions.
The surface profile is preferably configured in a manner where different points of the surface have different distances from the longitudinal axis of the second shifter element.
Preferably, the field has the effect that the movement of one of the shifter elements is opposed or assisted by a variable force.
A field in the sense of the present invention is preferably a potential field in which different positions are associated with different levels of potential energy. Preferably, the potential field is a force field. Further within the scope of the present invention, the term xe2x80x9cfieldxe2x80x9d can also mean a signal field in which different signals are generated by way of a field-sensing element or contact element that connects to different positions of the signal field. The signals are generated either by the field itself or by the field-sensing element.
The different signals are generated in particular by an arrangement where a spring-biased feeler element follows a surface profile on the second shifter element so that the compressive spring force varies as the feeler element moves over raised and depressed profile portions.
A field-sensing element in the sense of the present invention can be any element that has a connection to different locations of the field.
A connection between a field and a field-sensing element in the sense of the present invention means that the field-sensing element relates to a predetermined field location, with or without physical contact between the field-sensing element and the field location, so that the field-sensing element can in particular detect and transmit an attribute of the field location, such as a characteristic value. With preference, the field-sensing element communicates in each case with the field location that is situated in relation to the field-sensing element according to a predetermined characteristic.
The signal field is configured in particular as a binary signal field, meaning that the signal generated by the field alone or in cooperation with the field-sensing element can take on two different values.
Preferably, the redundant position-detecting device makes use of the field in order to determine the shift position of the transmission.
Also with preference, the redundant position-detecting device includes or is connected to a sensor device and/or a computer device. The sensor/computer device determines a field location and/or characteristic values of the field location according to a predetermined characteristic. Based on a correlation characteristic, the field location allows conclusions to be drawn with regard to the shift position of the transmission.
The field-sensing element is preferably part of an arrangement in the form of a retainer or holder containing the field-sensing element as well as a switch and/or sensor or the like. The switch/sensor can respond to or communicate with different positions of the field and will therefore also be referred to herein as a position transducer.
The position transducer can in particular be designed to detect a translatory movement of the field-sensing element as the latter follows the surface profile or other variable of the field.
The position transducer preferably generates a switch signal that is indicative of the shift position and/or a domain or delimited portion out of the overall range of shift movements. The term xe2x80x9cshift positionsxe2x80x9d specifically refers to predetermined positions of the gears or synchronizer elements or to a neutral position of the transmission.
The switch output signal is transmitted preferably to the control device or the actuator device. With preference, the control device takes the switch output signal into account when outputting command signals. With particular preference, the control device generates output command signals by taking into account the switch signal as well as signals of a primary position-detecting device, all of which are indicative of the current shift position of the transmission.
With preference, the surface profile of the second shifter element is configured so that a predetermined level of potential energy is assigned to each gear position and the neutral position of the transmission; and/or a predetermined level of potential energy is assigned to the selector track and each shift track.
The surface profile representing the level of potential energy is preferable measured or detected by a contact sensor or a field-sensing element that is part of the redundant position-detecting device. The level of potential energy is determined in particular by the distance of each surface point from the central axis of the second shifter element.
According to a preferred embodiment of the invention, at least one predetermined shift position such as a gear position or the neutral position or a track of the shift pattern is associated with a local extreme of the potential energy or of the surface profile. When the sensor or field-sensing element detects the local extreme value, this can be taken as an indication that the transmission is in the shift position associated with the local extreme.
Preferably, the field-sensing element is a sphere or spherical contact head that is spring-biased against a profiled surface, or the field-sensing element may be based on a non-contacting sensor principle.
According to a preferred embodiment of the invention, the field is configured so that the transmission has a tendency to move towards a local minimum of the potential energy even in the absence of a command signal from the control device, or without an actuator force being applied. In particular, the second shifter element can be arranged and configured so that it will seek a position where the energy stored in the biasing spring of a field-sensing element bearing against a surface profile of the second shifter element is minimized, i.e., a position where the field-sensing element bears against an area of minimum distance between the surface and the central axis of the second shifter element.
Preferably, the field is a scalar field or a vector field.
The field can be variable or invariable over time. A variable field may depend in particular on characteristic operating values of the motor vehicle or its constituent devices, which may change during the operation of the vehicle.
According to a preferred embodiment of the invention, the field or, more specifically, the field-like area or surface profile of the second shifter element correlates to a signal pattern which could be interpreted as a projection or a transformed image of the field that is overlaid on the track pattern of a selector track and shift tracks. The signal pattern is composed of different domains. A predetermined signal value is assigned to each domain, so that different signal values are generated depending on which domain the first shifter element is positioned in at a given time.
The signals associated with the different domains are at least in part different from each other. Preferably, there are two or three different signals assigned to the different domains.
The signal pattern is preferably used to determine which of the tracks of the shift pattern the first shifter element is positioned in at a given time.
With particular preference, the signal pattern is used to detect a movement of the first shifter element from a predetermined track to another predetermined track or from a predetermined gear position to another predetermined gear position. Preferably, the signal or signal value does not change within a domain.
According to a preferred embodiment of the invention, the signals that are associated with the domains of the signal pattern are used to determine
which of the tracks the first shifter element is currently positioned in;
whether the first shifter element is being moved from one predetermined track to another predetermined track;
whether the shifter element is being moved from a predetermined gear position to another predetermined gear position;
which of the gear levels is currently engaged.
The foregoing determination is made preferably on the basis of the number of signal changes that are detected in the course of a movement of the first shifter element and/or on the basis of the signal values that are assigned to the different domains of the signal pattern.
In a preferred embodiment of the invention, the field is used to determine when the transmission is in a position of synchronized gear engagement.
The domains of the signal pattern are preferably configured or arranged in such a way that at least one boundary between adjacent domains runs either parallel or perpendicular to a track of the shift pattern.
Preferably, a domain of the signal pattern covers the entire width of the track in which at least most of that domain is arranged.
A change in the signal detected by the sensor device occurs preferably when the first shifter element moves across a boundary between adjacent domains of the signal pattern. Preferably, the change consists of a jump from one signal state to another.
According to a preferred embodiment of the invention, the domains of the signal pattern are arranged in a chessboard-like configuration.
Preferably, the transmission is equipped with a computing device in which the topography of the signal pattern is stored. Based on the stored topographical data and the detected sensor signals, the computing device determines whether or when the first shifter element is moving to a different track of the shift pattern or the transmission is being shifted from one gear level to another.
With preference, the redundant position-detecting device has the capability of distinguishing certain predetermined shift positions of the transmission from other shift positions. Specifically, the distinctive shift positions include the fully engaged gear positions and/or the neutral position of the transmission.
According to a preferred embodiment of the invention, a movement of a first shifter element across a boundary between adjacent domains of the signal pattern is detected from the dynamic behavior of a predetermined characteristic operating value.
The characteristic operating value is in particular an electric current that is transmitted from the control device to an electric motor such as the selector motor or shifter motor.
With preference, the field or the surface profile is configured in such a way that the characteristic operating value, specifically the aforementioned electric current, undergoes a change, for example a jump from one level to another, at the time when the first shifter element is moved across a boundary between adjacent domains of the signal pattern.
Preferably, the field or profile on the second shifter element is configured in such a way that it has field portions in which a movement of the first shifter element is opposed by an essentially constant amount of resistance. In particular, the field or profile is shaped so that adjacent field portions are distinguished by different slope angles of the surface profile, but the slope angle inside each field portion is constant. The projections of the field portions coincide essentially with the domains of the signal pattern. Preferably, the electric current supplied to the selector motor and/or shifter motor by the control device is of a constant magnitude within a given field portion. Thus, an essentially jump-like change of the current will be detected at the transition from one field portion to another, which can be used as an indication that the shifter finger has crossed the boundary between adjacent domains of the signal pattern.
Preferably, the control device receives signals from the primary position-detecting device as well as the redundant position-detecting device to indicate the shift position of the transmission. The control device evaluates the signals for plausibility.
The invention proposes in particular for the case where the primary and redundant position-detecting devices are functioning correctly and their signals confirm each other, that the control device will control the transmission according to a normal operating mode, i.e., that the control device will generate output signals to the transmission in accordance with a normal operating characteristic.
In a particular embodiment of the invention, the system is shut down and/or a process of stopping the motor vehicle is initiated, if the primary and/or the redundant position-detecting device gives a faulty indication of the shift position. A predetermined characteristic can be used to detect whether the values furnished by one or both of the position-detecting devices are faulty. A condition where the primary position-detecting device is functional and the redundant position-detecting device is functionally impaired manifests itself in particular by the fact that the two position-detecting devices give different indications for the shift positions. In this case, a warning signal is generated to bring the malfunction to the attention of the driver of the vehicle.
If a condition is detected where the primary position-detecting device gives a faulty indication of the shift positions and the redundant position-detecting device gives a correct indication, the invention proposes with preference that the control device generate output signals according to a predetermined substitute characteristic. The substitute characteristic is designed to allow only shift processes that are compatible with the movement of the vehicle. In particular, shifts into certain predetermined gears are avoided.
The layout of the domains and/or domain boundaries of the signal pattern is designed preferably in accordance with the movement of the first and/or second shifter element. As a particular feature of the invention, the second shifter element is designed with a surface profile that is contacted by a spring-biased field-sensing element or feeler element. A switch in the signal from one state to another occurs when the feeler element is at a predetermined contour level of the surface profile, corresponding to a predetermined level of potential elastic energy of the biasing spring of the feeler element. As a particular feature, the direction is taken into account in which the threshold of the energy potential is crossed. In other words, a signal change is triggered if the second shifter element is in a position and moves in a way where the energy threshold is crossed in the direction from a higher to a lower potential, i.e., to an area of the surface profile closer to the central axis of the second shifter element. Alternatively, the signal change could also be triggered if the energy threshold is crossed in the direction from a lower to a higher potential energy.
The scope of the invention also includes a control device which performs the control functions required to operate the transmission according to the invention. The control device issues output signals in the form of commands to an actuator device that actuates the shift movements of the transmission according to a predetermined characteristic.
Also included in the scope of the invention are methods of operating a motor vehicle including a step of utilizing the transmission according to the invention, as well as methods including a step of utilizing a control device performing the control functions required to operate the inventive transmission.
The invention further proposes a method of shifting a transmission from a currently engaged gear level to a new gear level. The shift is actuated by a shift motor and a selector motor according to a predetermined characteristic. In the course of the shift process, the signals of a sensor device of the redundant position-detecting device are monitored and analyzed to determine the position of the first shifter element in relation to the track pattern. The shift from a given current gear to a given new gear determines a specific number of signal changes or a specific sequence of signals that will occur in the course of the shift process. Under the inventive method, the shift and/or actuator motor are activated dependent on the detected signals or signal changes.
As a linguistic formality, where the names of features are connected by the word xe2x80x9corxe2x80x9d, this should be understood in the broadest sense, i.e., either as a logic type of xe2x80x9corxe2x80x9d (meaning xe2x80x9cone or the other or bothxe2x80x9d) or an exclusive or (meaning xe2x80x9cone or the other but not bothxe2x80x9d), whichever fits the context.
The terms xe2x80x9ccontrolxe2x80x9d and xe2x80x9cregulationxe2x80x9d and their derivatives are used herein with a broad range of meanings encompassing closed-loop as well as open-loop control of devices, functions and processes, including in particular the DIN (Deutsche Industrie-Norm) definitions for regulation and/or control).
The novel features that are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.